Source Area, Depositional Environment, and Composition of Quaternary Sands, Monterey Bay, California: ABSTRACT

Abstract

A suite of 173 sand samples from the Monterey Bay region was studied, using a stepwise discriminant function analysis, to determine the role of source area and depositional environment in controlling the modal framework constituents of the sands. These medium to fine-grained sands were derived from the Salines, Pajaro, and Carmel drainage basins, and were deposited in fluvial, nearshore marine, and eolian environments. They range in age from recent to early Pleistocene. Provenance exerts the most significant control on composition, providing an 87% assignment efficiency (independent of depositional environment); volcanic and sedimentary rock fragments were the most important variables. There was a 100% efficiency when discriminating between fluvial sands from the three drainage basins; however, the efficiencies were less strong in marine and eolian sands (90.5 and 86%, respectively). This difference is, in part, the result of modification in transit and mixing of sources.